Heretofore, in a semiconductor or a liquid crystal manufacturing process, there have been used plasma apparatuses including a film formation apparatus to form a thin film on a substrate, such as a semiconductor wafer or a glass substrate, and an etching apparatus to perform microprocessing on a substrate. In the film formation apparatus, a raw material gas is steadily supplied and introduced into a reaction chamber and is then subjected to a chemical reaction, so that a thin film is formed on a substrate. In addition, in the etching apparatus, a halogenated corrosive gas is introduced therein as a raw material gas and is then plasmatized to be used as an etching gas, so that microprocessing is performed on a substrate.
As disclosed in Japanese Unexamined Patent Application Publication No. 2000-195807, those apparatuses each have a gas nozzle introduce a raw material gas. As the gas nozzle described above, a ceramic sintered body may be used. However, when a ceramic sintered body is used for the gas nozzle, although grinding processing and/or polishing processing is required to obtain a desired shape, the surface of the ceramic sintered body is damaged by the processing as described above, and hence particles are liable to fall off from the surface.
In addition, when the film formation apparatus or the etching apparatus is used, an end surface having a raw material-gas exhaust port of the gas nozzle is exposed to a gas in a reaction chamber and is damaged thereby, so that particles are liable to fall off from the end surface. When the particles are adhered to a substrate, defects are liable to be generated on the substrate in some cases.